This is an application for the re-competition of the Adolescent Medicine Trials Unit in San Francisco, a collaboration between the University of California San Francisco (UCSF) and Larkin Street Youth services (LSYS). San Francisco targets the key vulnerable populations outlined in the RFA: runaway homeless, substance abusing and minority youth, as well as transgender youth. Our aims remain to continue outreach to vulnerable youth both HIV infected and uninfected at risk and to engage them safely in clinical and behavioral research. We aim to continue creating a strong infrastructure for performing HIV vaccine trials in the future. We believe we contributed to the overall strength and breadth of the ATM and meet the expectations for renewal. Our site is an ATU centered in the community rather than the university;bringing university expertise in partnership to the community. Our primary clinical population of HIV positive youth receives medical care at Larkin Street Youth Services'(LSYS) community clinic, and we now have engaged more than 14 other community sites in recruitment and referrals into ATN studies. As of March 1, 2005 we have recruited 77 subjects into currently open clinical and prevention protocols at our site (021,022, 023B,024, 025, and 0168), have participated in several protocol development teams (015, 016B, 034, 039 and PACTG 1046), and a member of our staff was lead author on the first paper to be completed about Connect to Protect. UCSF Division of Adolescent Medicine is a rich resource for adolescent medicine research and clinical services to youth. The ATU at SF team includes the PI, Dr. Moscicki, our Connect to Protect (C2P)team members Catherine Geanuracos, LCSW, Kevin Sniecinski, and Dr. Colette Auerswald, Study Coordinators Bethany Certa, RN, BSN and J.B. Molaghan ANP-C, and staff assistant Nigel Reyes. At LSYS, Alan Taggart, M.D., has served HIV infected and uninfected youth at Larkin Street Youth for over nine years. He and Heather Weisbrod, the outreach worker, have effectively identified, screened and recruited homeless youth into trials. Our clinic services include LSYS, which has a comprehensive, youth centered, culturally appropriate model of HIV care, and, at UCSF, the Positive Health Practices and Pediatrics AIDS Program. In summary, our ATU site is a unique partnership between the university and the community. During the last 5 years, we have solidified our commitment to ensure marginalized and vulnerable youths'right to participate in research. The Connect to Protect project has expanded our involvement with the community and has brought additional agencies into our referral network. We believe it is critical to continue to engage the high risk youth in the San Francisco Bay Area in clinical and behavioral research.